A single serving method (from James Hoffman YT channel) I use is:

16g coffee 150g water 100g ice

I make the hot coffee using the above 16g coffee and 150g water. My brew time is four minutes. Then, I pour that hot coffee over the ice and stir until the ice cubes are melted.

Whiskey stones. Get solid stones or stainless steel ones. Ideally don't get any with liquid cores.

Have you tried freezing extra/left over coffee in an ice tray and using those to chill your coffee?

I double the amount of coffee I'd normally put in my French press, and then let it cool on the counter for a few hours.

I then fill 2 bottles half way with coffee and leave in the fridge over night. In the morning I top them up with ice and a little oat milk.

It starts off a little strong, but will taper down as the morning progresses and the ice melts.

Iced Mocha Madness: just add a meal replacement shake for those days when you don't have time to eat.

Sorry double posted- here is the other post where ppl gave more answers - https://lemmy.world/post/1357316

Some People may consider this sacrilege, but I keep a small jug in my fridge that I pour any extra coffee in. In brewing this would be the solvers method :). 1/4 cup left? It goes in the jug.

Then I use this to make iced coffee.

If I’m completely empty, I’ll brew a pot of French press, and then pour it in the jug to restock.

You might try the Toddy cold brew method. You take like a pound of beans, grind them up and soak in like a gallon of water that slow filters through a special filter they sell (reusable for 10 uses). Then you keep it in the fridge until you use it. It’s a more mellow, less acidic brew in general.

Cold brew shaken with lots of ice (and if you are me, some simple syrup). Cold brew is strong and smooth, and using more ice in shaker lowers the temp fast so less dilution. Strain over more ice in insulated cup.